1. Field of the Invention
The present invention relates to a reed valve cooling apparatus for an internal-combustion engine and, more particularly, to a reed valve cooling apparatus for an injector type engine to be mounted on a small planing boat.
2. Description of the Related Art
Referring to FIG. 8 showing a direct injection two-cycle engine provided with a reed valve in a vertical sectional view, an injector 14 is attached to a cylinder head 20 so as to inject fuel into a combustion chamber 21, and an intake port member 29 is formed integrally with a crankcase 18 so as to project diagonally upward from the crankcase 18. A reed valve 31 is fitted in the intake port member 29. The reed valve 31 has a flange 36 which is held between the joining surface 37 of the intake port member 29 and the joining surface 38 of an intake manifold 30. The intake manifold 30 is fastened to the intake port member 29 with bolts 42. A throttle body 43 provided with a throttle valve 44 is joined to the upper end of the intake manifold 30, and an air intake case 45 is connected to the throttle body 43.
The reed valve 31 has a valve case 32 of aluminum integrally provided with the flange 36, reeds 34 each having one end fixed to the base end of the valve case 32, and stoppers 35 of a metal for limiting the opening of the reeds 34. A heat insulating gasket 140 of, for example, paper is placed between the joining surface 37 of the intake port member 29 and the flange 36 of the reed valve 31.
The heat insulating gasket 140 is placed between the joining surface 37 of the intake port member 29 and the flange 36 of the reed valve 31 to retard conduction of heat from the engine to the reed valve 31. However, in some cases, it is difficult to prevent temperature rise in the reed valve 31 through heat insulation only by the heat insulating gasket 140. For example, in the direct injection type engine provided with the injector 14 as shown in FIG. 8 and not provided with any carburetor, the effect of fuel (air-fuel mixture)on cooling the reed valve 31 cannot be expected and hence it is difficult to prevent temperature rise in the reed valve 31. If the reed valve 31 is heated by heat transferred thereto by heat conduction or heat radiation, the strength of the reeds 34 is reduced. The strength of the reeds 34 can be increased by increasing the thickness of the reeds 34, which, however, deteriorates the response characteristic of the reeds 34.
Accordingly, it is an object of the present invention to provide a reed valve cooling apparatus capable of performing a forced cooling of a reed valve of an internal-combustion engine in order that the reed valve has satisfactory response characteristic and sufficient strength.
According to a first aspect of the present invention, a reed valve cooling apparatus for cooling a reed valve fitted in an intake port member formed on a crankcase of an internal-combustion engine, the reed valve having a flange placed between a joining surface of the intake port member and a joining surface of an intake pipe, the reed valve cooling apparatus includes:a water jacket formed in a circumferential wall of the intake port member; and a highly heat-conductive gasket placed between the joining surface of the intake port member and the flange of the reed valve.
Heat transferred from the crankcase to the intake port member can be dissipated by cooling water circulating through the water jacket. The reed valve can be effectively cooled by conduction of heat from the reed valve through the highly conductive gasket to the intake port member.
Preferably, the reed valve cooling apparatus further includes: a water jacket formed in a circumferential wall of the intake pipe; and a highly heat-conductive gasket placed between the joining surface of the intake pipe and the flange of the reed valve.
Both the intake port member and the intake pipe can be cooled. The reed valve can be cooled by conduction of heat from the reed valve through the highly conductive gaskets to the intake port member below the reed valve with respect to an air intake direction and from the reed valve to the intake pipe above the reed valve with respect to the air intake direction.
Preferably, the engine is provided with an injector disposed at a position above the reed valve with respect to a flowing direction of an intake air or on a cylinder head.
Preferably, the engine is adapted to be installed on a craft for traveling on a water; and a cooling water for the water jacket is supplied from an ambient water.
According to the second aspect of the present invention, a reed valve cooling apparatus for cooling a reed valve fitted in an intake port member formed on a crankcase of an internal-combustion engine, the reed valve having a flange placed between a joining surface of the intake port member and a joining surface of an intake pipe, the reed valve cooling apparatus includes: a water jacket formed in a circumferential wall of the intake pipe; a highly heat-conductive gasket placed between the joining surface of the intake pipe and the flange of the reed valve; and a heat-insulating gasket placed between the joining surface of the intake port member and the flange of the reed valve.
The intake pipe can be effectively cooled. The reed valve can be cooled by conduction of heat from the reed valve through the highly conductive gasket to the intake pipe. Heat conduction from the intake port member to the reed valve can be effectively retarded by the heat-insulating gasket.
Preferably, the engine is provided with an injector disposed at a position above the reed valve with respect to a flowing direction of an intake air or on a cylinder head.
Preferably, the engine is adapted to be installed on a craft for traveling on a water; and a cooling water for the water jacket is supplied from an ambient water.
According to the third aspect of the present invention, an internal-combustion engine includes: a crankcase; an intake port member formed on the crankcase, the intake port member having a circumferential wall and a joining surface; an intake pipe joined to the intake port member, the intake pipe having a circumferential wall and a joining surface; a reed valve fitted in the intake port member, the reed valve having a flange placed between the joining surface of the intake port member and the joining surface of the intake pipe; and a reed valve cooling apparatus having a water jacket formed in the circumferential wall of the intake port member and a highly heat-conductive gasket placed between the joining surface of the intake port member and the flange of the reed valve.
Preferably, the reed valve cooling apparatus further includes: a water jacket formed in the circumferential wall of the intake pipe; and a highly heat-conductive gasket placed between the joining surface of the intake pipe and the flange of the reed valve.
Preferably, the internal-combustion engine further includes:
a cylinder head; and an injector disposed at a position above the reed valve with respect to a flowing direction of an intake air or on the cylinder head.
Preferably, the engine is adapted to be installed on a craft for traveling on a water; and a cooling water for the water jacket is supplied from an ambient water.
According to the fourth aspect of the present invention, an internal-combustion engine includes: a crankcase; an intake port member formed on the crankcase, the intake port member having a circumferential wall and a joining surface; an intake pipe joined to the intake port member, the intake pipe having a circumferential wall and a joining surface; a reed valve fitted in the intake port member, the reed valve having a flange placed between the joining surface of the intake port member and the joining surface of the intake pipe; and a reed valve cooling apparatus having a water jacket formed in the circumferential wall of the intake pipe; a highly heat-conductive gasket placed between the joining surface of the intake pipe and the flange of the reed valve; and a heat-insulating gasket placed between the joining surface of the intake port member and the flange of the reed valve.
Preferably, the internal-combustion engine further includes:
a cylinder head; and an injector disposed at a position above the reed valve with respect to a flowing direction of an intake air or on the cylinder head.
Preferably, the engine is adapted to be installed on a craft for traveling on a water; and a cooling water for the water jacket is supplied from an ambient water.
When an internal-combustion engine has an injector disposed at a position above the reed valve with respect to a flowing direction of an intake air or in the cylinder head, only air or air containing a small amount of oil flows through the reed valve and the cooling effect of fuel cannot be expected. However, the reed valve cooling apparatus of the present invention can cool the reed valve using cooling water with a result that temperature rise in the reed valve can be effectively suppressed. Therefore, the reed valve can be provided with a strong reed having a satisfactory response characteristic.